| Historically, electrochemical detection methods for the chlorinated phenol (CP's) analysis have been plagued by fouling of the electrode. Diamond is a new electrode material that shows little tendency to be deactivated and fouled by adsorbed reaction products and intermediates during the oxidation of CP's. This new electrode reopens the door to electrochemical detection of these pollutants. In this work cyclic voltammetry with microcrystalline and nanocrystalline diamond electrodes was used to study the chlorophenol oxidation reaction in acidic media and to learn how the film morphology might affect the reaction mechanism. Amperometry with both diamond types was coupled with flow injection analysis, high performance liquid chromatography (HPLC-EC), and capillary zone electrophoresis (CE-EC), for the analysis of chlorinated phenols.; Diamond electrodes exhibited good responsiveness for the electro-oxidation of these compounds and resisted fouling during extended use. The electrode performance was evaluated in terms of the linear dynamic range, limit of quantitation, response precision and response stability. Both diamond types exhibited excellent detection figures of merit. For example in HPLC-EC, the limit of quantitation for the 2-chlorophenol was 0.1 muM (13 ppb) with a response precision of 4.1% (n = 7) for the microcrystalline diamond electrode. In CE-EC using diamond microelectrode, the limit of quantitation for 2-chlorophenol was 0.1 muM (13 ppb) and the response precision was 4.7% (n = 9).; Real samples were also analyzed. The HPLC-EC assay was used for the determination of 2-chlorophenol in a contaminated soil sample. Red Cedar water was spiked with CP's and was extracted by solid phase extraction (SPE) prior to analysis, and then assayed for using CE-EC. This lowered the limit of quantitation to mid to high ppt range. The results demonstrate that electrochemical detection methods using diamond electrode can be employed for the analysis of CP's. |
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